Nadiyah, tag is a game where someone is "it". The person who is it must run and tag (touch) someone else. When you tag someone, you say, "You're it!" In the game it means, it's your turn to do the chasing! In this game it means it's your turn to answer a tag question! (This is called a "play on words".)
So, I wrote a tag question for you: "You think I am a man, don't you?" When I said "you're it" that meant it's your turn to come and play!

Here's another one for you Nadiyah: "You like to change your avatar regularly, don't you?"